Wireless communication terminal and handoff determination method

ABSTRACT

A wireless communication terminal includes a measurement section that measures quality of a signal transmitted from a base station, a determination section that determines whether or not handoff is to be performed based on a measurement result of the measurement section and a criterion of the determination of the handoff, and handoff section that performs the handoff based on a determination result of the determination section, wherein the determination section changes the criterion of the determination of the handoff when the handoff section performs the handoff in a predetermined repetition pattern.

TECHNICAL FIELD

The invention relates to a wireless communication terminal, and moreparticularly, to a wireless communication terminal capable of reducingunnecessary idle handoff and to a handoff determination method thereof.

BACKGROUND ART

It is known that a wireless communication terminal communicating with abase station measures the quality of communication (ReceivedSignal/Strength Indicator, Signal-to-Interference Ratio (SIR) value,error rate, or the like) with the base station by using an idle slot andperforms handoff to another base station on the basis of the measurementresult.

In order to perform the handoff, it is necessary to exchange severalmessages so that the wireless communication terminal can performprocessing, such as registration of the terminal in a new base station,after the handoff.

Patent Document 1: JP-B-H5-73297

Particularly, in handoff (idle handoff) to be performed while thewireless communication terminal is an idle state condition, when thequality of communication with another base station has become superiorto that of the base station with which the wireless communicationterminal is currently in an idle state condition, the wirelesscommunication terminal determines that the idle handoff is necessary andperforms the idle handoff to the another base station which providessuperior communication quality.

At this time, for instance, the communication qualities of the two basestations contend with each other, and when the relative rankings of thetwo communication qualities frequently reverse within a short period oftime, the idle handoff arises frequently.

This state is shown in FIG. 4.

Even when the communication quality of the base station (A) issufficiently superior to that of another base station (B), thecommunication quality of the base station (B) becomes superior to thatof the base station (A) as a result of the communication quality of thebase station (A) having been considerably deteriorated duringmeasurement for reasons of instantaneous disconnection of a radio waveor the like. Consequently, the idle handoff arises. However, thecommunication quality of the base station (A) recovers immediately,whereupon the idle handoff again arises.

This state is shown in FIG. 5.

DISCLOSURE OF INVENTION

The invention has been conceived in view of the previously-describeddrawbacks and aims at providing a wireless communication terminal whichlessens frequency of occurrence of idle handoff even when communicationqualities of a plurality of base stations or sectors contend with eachother and the relative rankings of communication qualities frequentlyreverse within a short period of time.

A first invention is characterized by having a measurement section thatmeasures quality of a signal transmitted from a base station; adetermination section that determines whether or not handoff is to beperformed based on a measurement result of the measurement section and acriterion of the determination of the handoff; and a handoff sectionthat performs the handoff based on a determination result of thedetermination section, wherein the determination section changes thecriterion of the determination of the handoff when the handoff sectionperforms the handoff in a predetermined repetition pattern.

A second invention according to the first invention is characterized inthat the determination section changes the criterion of thedetermination of the handoff when a predetermined repetition of twopilot signals is acquired.

A third invention according to the second invention is characterized inthat, when qualities of the two pilot signals acquired repeatedly areequal to or greater than a predetermined value, the criterion of thedetermination of the handoff is changed.

A fourth invention is characterized by further having a detectionsection that detects time during which a preceding pilot signal isacquired every time handoff is performed, wherein the determinationsection changes the criterion of the determination of the handoff basedon the time detected by the detection section.

A fifth invention is characterized by having a measurement section thatmeasures quality of a signal transmitted from a base station; adetermination section that determines whether or not handoff is to beperformed based on a measurement result of the measurement section and acriterion of the determination of the handoff; and a handoff sectionthat performs the handoff based on a determination result of thedetermination section, wherein the determination section determineswhether or not the handoff is to be performed based on a value obtainedby time-averaging the measurement result of the measurement sectionimmediately after the handoff is performed, and determines whether ornot the handoff is to be performed based on a value obtained bynumber-averaging the measurement result of the measurement section aftera lapse of a predetermined period since the handoff is performed.

A sixth invention according to any of the first through fifth inventionsis characterized in that the wireless communication terminal enables tobe in an idle state condition with both methods of cdma2000 1x methodand 1xEVDO method, and the determination section is used as section fordetermining a handoff of cdma2000 1x method.

A seventh invention is characterized by a method of a wirelesscommunication terminal which performs wireless communication with basestations using each of a first communication method and a secondcommunication method and enables to be in an idle state condition withboth methods, the handoff determination method involving the steps of:measuring quality of a signal transmitted from a base station;determining whether or not a handoff is to be performed based on ameasurement result and a criterion of the determination of the handoff;performing the handoff based on a determination result; and changing thecriterion of the determination of the handoff when the handoff sectionperformed the handoff in a predetermined repetition pattern.

An eighth invention according to the seventh invention is characterizedin that the criterion of the determination of the handoff is changedwhen two pilot signals are repeatedly acquired.

A ninth invention according to the eighth invention is characterized inthat, when qualities of the two pilot signals acquired repeatedly areequal to or greater than a predetermined value, the criterion of thedetermination of the handoff is changed.

A tenth invention according to the seventh invention is characterized inthat time during which a preceding pilot signal is acquired is detectedevery time handoff is performed, and the criterion of the determinationof the handoff is changed based on the detected time.

An eleventh invention is characterized by involving the steps of:measuring quality of a signal transmitted from a base station;determining whether or not a handoff is to be performed based on ameasurement result and a criterion of the determination of the handoff;and performing the handoff based on a determination result, whereinwhether or not the handoff is to be performed is determined based on avalue obtained by time-averaging the measurement result of themeasurement section immediately after the handoff is performed, andwhether or not the handoff is to be performed is determined based on avalue obtained by number-averaging the measurement result themeasurement section after a lapse of a predetermined period since thehandoff is performed.

A twelfth invention is characterized in that the handoff determinationmethod is used for a wireless communication terminal which enables to bein an idle state condition with both methods of cdma2000 1x method and1xEVDO method, and whether or not handoff of a cdma2000 1x method is tobe performed is determined.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the configuration of a wirelesscommunication terminal according to a first embodiment of the invention;

FIG. 2 is a flowchart showing idle handoff processing procedures of thefirst embodiment of the invention;

FIG. 3 is a flowchart showing idle handoff processing procedures of asecond embodiment of the invention;

FIG. 4 is a timing chart showing a relationship between the quality ofcommunication with base stations and idle handoff in a conventionalcommunication terminal; and

FIG. 5 is a similar timing chart showing a relationship between thequality of communication with base stations and idle handoff in theconventional communication terminal.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be described hereinbelow by referenceto the drawings.

FIG. 1 is a block diagram showing the configuration of a wirelesscommunication terminal according to a first embodiment of the invention.

The wireless communication terminal of the embodiment is a wirelesscommunication terminal which can perform communication while moving, bymeans of selectively switching between a communication system ofcdma2000 1x method and a communication system of 1xEVDO (1x EvolutionData Only) method to perform handoff with a base station 101A and a basestation 100B.

An antenna 10 transmits to the base stations (100A), (100B) highfrequency signals received from a radio section 20, and receives radiowaves output from the base stations (100A), (100B) to transmit the radiowaves to the radio section 20 as high-frequency signals.

The radio section 20 converts the high-frequency signals transmittedfrom the antenna 10 into base band signals and sends the base bandsignals to radio processing sections 40, 50 through a switching section30. Further, the radio section 20 converts base band signals transmittedfrom the radio processing sections 40, 50 through the switching section30 into high-frequency signals to send the high-frequency signals to theantenna 10.

The switching section 30 selectively transmits the base band signalsoutput from the 1xEVDO radio processing section 40 or the cdma2000 1xradio processing section 50 to the radio section 20. Further, theswitching section 30 selectively sends the base band signals output fromthe radio section 20 to the 1xEVDO radio processing section 40 or thecdma2000 1x radio processing section 50.

The 1xEVDO radio processing section 40 converts data signals transmittedin 1xEVDO format into base band signals, and sends the base band signalsto the radio section 20 through the switching section 30.

Moreover, the 1xEVDO radio processing section 40 converts base bandsignals transmitted from the radio section 20 through the switchingsection 30 into data signals in 1xEVDO format.

Like the 1xEVDO radio processing section 40, the cdma2000 1x radioprocessing section 50 converts data or audio signals transmitted incdma2000 1x format into base band signals to send the base band signalsto the radio section 20 through the switching section 30.

Moreover, the cdma2000 1x radio processing section 50 converts base bandsignals transmitted from the radio section 20 through the switchingsection 30 into data or audio signals in cdma2000 1x format.

A hybrid section 60 is a control section for controlling the twocommunication systems by means of selectively switching between the twocommunication systems; that is, 1xEVDO system and cdma2000 1x system.The hybrid section 60 is connected to the switching section 30, the1xEVDO radio processing section 40, and the cdma2000 1x radio processingsection 50, thereby controlling switching thereof.

Particularly, the two communication systems are selectively switched atpredetermined time intervals during an idle state condition, and bothcommunication systems await calls from the base stations (100A), (100B).The hybrid section 60 is connected to a memory 70, a display section 80,and an external I/O 90.

The memory 70 is a storage section which enables writing or reading ofcommunication data, a program for controlling the wireless communicationterminal, or the like.

The display section 80 is a display section which is mainly configuredfrom an LCD display or the like and displays the status of the wirelesscommunication terminal and communication data.

The external I/O 90 is an interface which connects the wirelesscommunication terminal to an external equipment such as a personalcomputer or a PDA, thereby enabling to transmit and receive variousdata.

Operation of the wireless communication terminal of the first embodimenthaving the foregoing configuration will now be described.

The wireless communication terminal of the first embodiment isconfigured such that the communication qualities (C/I values) of the twopilot signals A, B are sufficiently high to perform communication andsuch that the frequency of occurrence of the idle handoff (see FIG. 4)frequently arising with the two C/I values contending each other isreduced.

More specifically, the wireless communication terminal performs aprocessing for changing a threshold value used for determining whetheror not the idle handoff is to be performed.

FIG. 2 shows a procedure for setting the threshold value of the idlehandoff for reducing the frequency of occurrence of the idle handoff.

First, a currently-monitored pilot signal is taken as n, a pilot signalpreceding occurrence of last idle handoff is taken as n−1, a pilotsignal preceding occurrence of second last idle handoff is taken as n−2,. . . .

It is determined whether or not the currently-monitored pilot signal n,the pilot signal n−2 before the second last idle handoff, and a pilotsignal n−4 before the fourth last idle handoff are all equal to eachother (step 101).

If the currently pilot signal n, the pilot signal n−2 before the secondlast idle handoff, and the pilot signal n−4 before the fourth last idlehandoff are all equal to each other, it proceeds to step 102.

If any of the currently-monitored pilot signal n, the pilot signal n−2before the second last idle handoff, and the pilot signal n−4 before thefourth last idle handoff differs from the others, it proceeds to step105, where a threshold value for ordinary idle handoff is set, and theprocedure completes.

In step 102, it is determined whether or not the pilot signal n−1 beforethe last idle handoff, a pilot signal n−3 before third last idlehandoff, and a pilot signal n−5 before fifth last idle handoff are equalto each other.

If the pilot signal n−1 before the last idle handoff, the pilot signaln−3 before the third last idle handoff, and the pilot signal n−5 beforethe fifth last idle handoff are all equal to each other, it proceeds tostep 103.

If any of the pilot signal n−1 before the last idle handoff, the pilotsignal n−3 before the third last idle handoff, and the pilot signal n−5before the fifth last idle handoff differs from the others, it proceedsto step 105, where the threshold value for the ordinary idle handoff isset, and the procedure completes.

That is, through the processing shown in FIG. 2 for setting a thresholdvalue, it is determined that the handoff have repeatedly arisen in asingle pilot signal in each step 101, 102.

Next, in step 103, it is determined whether or not a C/I value (A) ofthe current pilot signal and a C/I value (B) of the pilot signal beforethe last idle handoff are greater than a preset value α.

If the C/I values of the two pilot signals are greater than α, itproceeds to step 104.

If the C/I values of the two pilot signals are sufficiently large, thequalities of the pilot signals are superior. Thus, communication withonly one of the pilot signals is sufficient so that it is unnecessary toperform the idle handoff.

If the C/I values of the two pilot signals are smaller than α, thethroughput of communication is improved by communicating with the pilotsignal having the larger C/I value. Therefore, the threshold value ofthe ordinary idle handoff is set (step 105).

The value of α is previously determined through a test or the like suchthat the best communication throughput is attained in terms of arelationship between the frequency of occurrence of the idle handoff andthe C/I value.

There will now be described changing, in step 104, the threshold valuefor determining whether or not idle handoff is to be performed.

When the two pilot signals are alternately switched at least twicethrough the idle handoff by means of the processing pertaining to steps101 to 103 and when the C/I values of the radio waves of the two pilotsignals are sufficiently greater than α, the threshold value of the idlehandoff is changed to a value at which the idle handoff does not arisefrequently (step 104).

For instance, the threshold value used for determining whether or notthe ordinary idle handoff is to be performed is assumed to be γ, a valueγ′ obtained by addition of a predetermined value X to γ is used fordetermining whether or not the idle handoff is to be performed.

In steps 101 and 102 described above, it is determined whether or notswitching between the pilot signal A and the pilot signal B has beenmade twice. However, the determination may be made as to whether or notthe switching is repeated once.

In the wireless communication terminal of the first embodiment havingthe foregoing configuration, when the C/I values of the two pilotsignals are greater than a predetermined value and when occurrence ofthe idle handoff to be repeatedly effected a predetermined number oftimes has been detected, the threshold value for determining the idlehandoff is changed such that the number of times the idle handoff arisesis reduced, in order to reduce the frequency of occurrence of the idlehandoff frequently arising when the C/I values of the two pilot signalscontend with each other.

As a result, the burden imposed on the base station and that imposed onthe wireless communication terminal can be diminished, wherebyconsumption of a battery of the wireless communication terminal can besuppressed.

As in the case of the present embodiment, the wireless communicationterminal of hybrid type can diminish the time during which onecommunication system occupies the radio section 20 by repeated idlehandoff processing. Thus, a communication throughput of anothercommunication system can be enhanced.

A wireless communication terminal according to a second embodiment ofthe invention will now be described.

As shown in FIG. 5, in the conventional wireless communication terminal,when “instantaneous interruption” in which the pilot signal A isinstantaneously interrupted under the situation where the C/I value ofthe pilot signal A is sufficiently large and where the C/I value of theother pilot signal B is smaller than that of the pilot signal A, the C/Ivalue of the pilot signal A becomes considerably small during the periodof the instantaneous interruption of the radio wave.

Consequently, since the C/I value of the pilot signal B becomes greaterthan that of the pilot signal A, the wireless communication terminalwhich has measured the communication quality at this time determines torequire the idle handoff, and the idle handoff is performed.

However, when the instantaneous interruption is temporary and thecommunication quality of the pilot signal A has recovered immediately,the C/I value of the pilot signal A becomes greater than that of thepilot signal B, and the idle handoff arises again.

Thus, the idle handoff arises twice within a short period of time.Accordingly, the idle handoff frequently arises under a situation wherethe instantaneous interruption of the pilot signal A arises frequently.

In the wireless communication terminal of the second embodiment of theinvention, a method of determining whether or not the idle handoff is tobe performed is changed so as to reduce the frequency of occurrence ofthe idle handoff which arises a plurality of times within a short periodof time as a result of the instantaneous interruption of radio wave.

FIG. 3 shows a procedure for setting the idle handoff of the secondembodiment.

In step 201, it is determined how the idle handoff has arisen.

Specifically, it is determined whether the idle handoff has arisentwice, and the pilot signal is switched from the pilot signal A toanother pilot signal (X) at this time, and is then returned from theother pilot signal (X) to the pilot signal A.

If it is determined that the pilot signal is switched so as to return tothe same pilot signal (A-X-A), it proceeds to step 202.

If not, it proceeds to step 203, where a threshold value of ordinaryidle handoff is set.

In step 202, the time during which the pilot signal has switched to themonitored pilot signal X until returning to the same pilot signal iscompared with a predetermined value β.

If the comparison result shows that the time during which the pilotsignal X is monitored is shorter than β, it proceeds to step 204. If thetime is longer than β, it proceeds to step 203, where the thresholdvalue of the ordinary idle hand off is set.

In step 204, it is determined whether or not the current state is anintermittently-receiving state.

If the current state is the intermittently-receiving state, it proceedsto step 210. If the current state is not the intermittently-receivingstate, it proceeds to step 205.

In step 205, the communication quality (C/I value) of the current pilotsignal A and the communication quality (C/I value) of the previous pilotsignal X are measured for a predetermined period of time, andmeasurement results are stored.

Next, a time mean value of the C/I values of the pilot signal A and thatof the C/I values of the pilot signal X, both signals being measured instep 206, are determined as a and x (step 206).

A value x′ is then obtained by subtracting a predetermined value α fromthe mean value x of the C/I values of the previous pilot signal X (step207). The α is a threshold value for determining whether or not the idlehandoff is to be performed. For instance, when a difference between aC/I value of a currently-monitored pilot signal C and a C/I value ofanother pilot signal D has become larger than the threshold value α,idle handoff from the pilot signal C to the pilot signal D is performed.

Next, x′ is compared with a. If x′ is greater than a, it proceeds tostep 209, where the idle handoff is performed.

On the other hand, If x′ is smaller than a, it returns to step 204 (step208).

In the processing of step 208, only when the value x′ determined as aresult of subtraction of the predetermined threshold value α from themean value x of the C/I value of the previous pilot signal X is greaterthan the mean value a of the C/I value of the current pilot signal A(when x is larger than a by α or more), it is determined the idlehandoff is required, and the idle handoff is performed.

Specifically, a determination as to whether or not the idle handoff isto be performed is made not on the basis of the C/I value achieved atthat time, but on the basis of a mean value of the C/I value acquiredwithin a predetermined period of time. When the time mean value hasbecome greater than the threshold value α, processing of the idlehandoff is performed.

In step 209, the processing of the idle handoff is performed.

When it is determined that the current state is theintermittently-receiving state in step 204, the communication quality(C/I value) of the current pilot signal A and the communication quality(C/I value) of the previous pilot signal X are measured a predeterminednumber of times, and measurement results are stored in step 210.

Next, a mean value of the C/I values of the pilot signal A and that ofthe C/I values of the pilot signal X, both signals being measured instep 210, are determined as a_(M) and x_(M) (step 211).

A value x_(M)′ is then obtained by subtracting a predetermined value αfrom the mean value x_(M) of the C/I values of the previous pilot signalX (step 212).

Next, x_(M)′ is compared with a_(M). When x_(M)′ is greater than a_(M),it proceeds to step 209, where the idle handoff is performed. Whenx_(M)′ is smaller than a_(M), it returns to step 204 (step 213).

Specifically, a determination as to whether or not the idle handoff isto be performed is made not on the basis of the C/I value determinedfrom a single measurement result, but on the basis of a means value ofthe C/I values determined through a predetermined number of measurement.

In the invention, in the case where disconnection and return idlehandoff have arisen, the processing is performed so as to perform theidle handoff only when the time of the previously-monitored pilot signalis shorter than a predetermined time and when the time mean value of theC/I values of the currently-monitored pilot signal is greater than thetime mean value of the C/I values of the previous pilot signal by only apredetermined threshold value.

In the intermittently-receiving state, the C/I value of thecurrently-monitored pilot signal and the C/I value of the pilot signalpreviously-monitored are compared with the mean value of the C/I valuesobtained through a predetermined number of measurement. Only when theC/I value of the previously-monitored pilot signal is greater than theC/I value of the currently-monitored pilot signal by a predeterminedthreshold value or more, the idle handoff is performed. Therefore, theidle handoff can be prevented from arising frequently even under thesituation where the communication quality of one pilot signal is betterthan the communication quality of another pilot signal and where theinstantaneous interruption occurs to the one pilot signal.

Consequently, as in the case of the first embodiment, the burden imposedon the base station and that imposed on the wireless communicationterminal can be diminished, whereby consumption of a battery of thewireless communication terminal can be suppressed.

Moreover, as in the case of the present embodiment, the wirelesscommunication terminal of hybrid type can diminish the time during whichone communication system occupies the radio section 20 by repeated idlehandoff processing. Thus, the communication throughput of anothercommunication system can be enhanced.

The wireless communication terminals of the first and second embodimentsemploy a C/I value for determining whether or not the idle handoff is tobe performed. RSSI (Received Signal/Strength Indicator) may be employed.

The wireless communication terminals of the first and second embodimentsare explained as hybrid type wireless communication terminals which isin an idle state condition with both systems, that is, the cdma2000 1xsystem and the 1xEVDO system. It may also be applied to a wirelesscommunication terminal using another communication system.

The threshold value α is not limited to subtraction but may be subjectedto same function. Thus, the threshold value α is not limited to theembodiments.

The invention has been described in detail by reference to specificembodiments. However, as is obvious to a person skilled in the art, theinvention can be subjected to various modifications or correctionswithout departing from the sprint and scope thereof.

The present patent application is based on Japanese Patent Application(Patent Application No. 2003-11539) filed on Jan. 20, 2003, anddescriptions of the application are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

According to the invention, the frequency of occurrence of idle handoffwhich frequently arises within a short period of time can be reduced. Asa result, the burden imposed on the base station and that imposed on thewireless communication terminal can be diminished, and consumption of abattery of the wireless communication terminal can also be reduced.Moreover, a communication throughput of a communication system can beimproved.

1. A wireless communication terminal comprising: a measurement sectionthat measures quality of a signal transmitted from a base station; adetermination section that determines whether or not handoff is to beperformed based on a measurement result of the measurement section and acriterion of the determination of the handoff; and a handoff sectionthat performs the handoff based on a determination result of thedetermination section, wherein the determination section changes thecriterion of the determination of the handoff when the handoff sectionperforms the handoff in a predetermined repetition pattern.
 2. Thewireless communication terminal according to claim 1, wherein thedetermination section changes the criterion of the determination of thehandoff when a predetermined repetition of two pilot signals isacquired.
 3. The wireless communication terminal according to claim 2,wherein when qualities of the two pilot signals acquired repeatedly areequal to or greater than a predetermined value, the criterion of thedetermination of the handoff is changed.
 4. The wireless communicationterminal according to claim 1, further comprising: a detection sectionthat detects time during which a preceding pilot signal is acquiredevery time handoff is performed, wherein the determination sectionchanges the criterion of the determination of the handoff based on thetime detected by the detection section.
 5. A wireless communicationterminal comprising: a measurement section that measures quality of asignal transmitted from a base station; a determination section thatdetermines whether or not handoff is to be performed based on ameasurement result of the measurement section and a criterion of thedetermination of the handoff; and a handoff section that performs thehandoff based on a determination result of the determination section,wherein the determination section determines whether or not the handoffis to be performed based on a value obtained by time-averaging themeasurement result of the measurement section immediately after thehandoff is performed, and determines whether or not the handoff is to beperformed based on a value obtained by number-averaging the measurementresult of the measurement section after a lapse of a predeterminedperiod since the handoff is performed.
 6. The wireless communicationterminal according to any one of claims 1 to 5, wherein the wirelesscommunication terminal enables to be in an idle state condition withboth methods of cdma2000 1x method and 1xEVDO method, and thedetermination section is used as section for determining a handoff ofcdma2000 1x method.
 7. A handoff determination method of a wirelesscommunication terminal which performs wireless communication with basestations using each of a first communication method and a secondcommunication method and enables to be in an idle state condition withboth methods, the handoff determination method comprising the steps of:measuring quality of a signal transmitted from a base station;determining whether or not a handoff is to be performed based on ameasurement result and a criterion of the determination of the handoff;performing the handoff based on a determination result; and changing thecriterion of the determination of the handoff when the handoff sectionperforms the handoff in a predetermined repetition pattern.
 8. Thehandoff determination method according to claim 7, wherein the criterionof the determination of the handoff is changed when two pilot signalsare repeatedly acquired.
 9. The handoff determination method accordingto claim 8, wherein when qualities of the two pilot signals acquiredrepeatedly are equal to or greater than a predetermined value, thecriterion of the determination of the handoff is changed.
 10. Thehandoff determination method according to claim 7, wherein time duringwhich a preceding pilot signal is acquired is detected every timehandoff is performed, and the criterion of the determination of thehandoff is changed based on the detected time.
 11. A handoffdetermination method comprising the steps of: measuring quality of asignal transmitted from a base station; determining whether or not ahandoff is to be performed based on a measurement result and a criterionof the determination of the handoff; and performing the handoff based ona determination result, wherein whether or not the handoff is to beperformed is determined based on a value obtained by time-averaging themeasurement result of the measurement section immediately after thehandoff is performed, and whether or not the handoff is to be performedis determined based on a value obtained by number-averaging themeasurement result of the measurement section after a lapse of apredetermined period since the handoff is performed.
 12. The handoffdetermination method according to any one of claims 7 to 11, wherein thehandoff determination method is used for a wireless communicationterminal which enables to be in an idle state condition with bothmethods of cdma2000 1x method and 1xEVDO method, and whether or nothandoff of the cdma2000 1x method is to be performed is determined.